The official Galaxy S II press conference has only just begun (it's streaming live now), but all 3 carriers we've been expecting to see the S II on - Sprint, AT&T, and T-Mobile - have already sent out their press releases.

The Galaxy SII is already available in Europe and Korea, debuting as Samsung's fastest selling smartphone to date. The 3 variants in the U.S. will share many of the same specs, but some aspects, such as the screen sizes, battery capacities, and mobile radios, will be different.

Here are some of the common specs:

Blazing fast 1.2GHz dual-core Exynos processor

Super AMOLED Plus display

8MP camera capable of 1080p video - the S II takes some of the best video we've seen on any phone

2MP front-facing camera

16GB built-in storage

microSD card slot with support for 32GB

HDMI out at 1080p

Android 2.3 (most likely 2.3.4)

4G of some kind (HSPA+ on T-Mobile and AT&T, WiMax on Sprint)

802.11 a/b/g/n Wi-Fi

On-device encryption of user data

Voice Talk voice commands (this is not the same as Google Voice Search)

Screen Capture built right in (press the Power+Home keys simultaneously)

One specific spec worth highlighting is Samsung's Exynos processor, which should be quite a bit faster than the Tegra 2 that most dual-core phones have been using so far (with the exception of the TI OMAP on a few models). At 1.2GHz, the 2 cores should be mind-blowingly fast - faster than anything we here in the U.S. have experienced before.

Sprint will be offering the SII (labeled as the Epic 4G Touch) starting September 16th, at $199 for a new two-year agreement. The other two providers have yet to reveal their planned release dates (AT&T's released is rumored to be September 18th), but you can bet they will be at least somewhat in line with Sprint.

Below, I've highlighted (in bold) some of the specs that vary between the three devices.

Sprint Galaxy S II Epic 4G Touch

Here are the official specs for Sprint's SII:

Samsung Exynos™ 1.2GHz dual-core processor

4.52" Super AMOLED Plus display

800x480 WVGA resolution - yikes, we were hoping for a bit more on such a large screen

Samsung Media Hub features thousands of new releases and top-grossing titles from major Hollywood studios and leading TV networks, including NBC Universal, Paramount, MTV, Warner Bros., CBS and FOX.

Samsung Social Hub allows users to transfer email, instant messaging, contacts, calendar and social network connections, including Twitter, Facebook and LinkedIn accounts, into “Feeds” and “Messages” folders that can be either put into separate tabs or combined into comprehensive lists.

Dimensions: 2.7 inches x 5.1 inches x 0.38 inches (LxWxT)

Battery: 1800 mAh Lithium-ion battery

Weight: 4.55 ounces

The Epic 4G Touch will be available September 16th for $199.99.

AT&T Galaxy S II

And here are AT&T's official specs:

4G – HSPA+

Android (2.3 Gingerbread)

GSM Quad-band (850/900/1800/1900MHz)

UMTS Tri-band( 850/1900/2100MHz)

16GB of on-board memory, as well as a microSD card slot that supports up to a 32GB memory card.